Arborescent Polymers with a Mesoscopic Scale

Department of Chemistry, Institute for Polymer Research, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada 

Branched macromolecules fall into three main classes star-branched polymers, characterized by multiple chains linked at one central point (Roovers, 1985), comb-branched polymers, having one linear backbone and side chains randomly distributed along it (Rempp et al., 1988), and dendritic polymers, with a multilevel branched architecture (Tomalia and Frechet, 2001). The cascade-branched structure of dendritic polymers is typically derived from polyfunctional monomers under more or less strictly controlled polymerization conditions. This class of macromolecules has a unique combination of features and, as a result, a broad spectrum of applications is being developed for these materials in areas including microencapsulation, drag delivery, nanotechnology, polymer processing additives, and catalysis. 

Complex Macromolecular Architectures Synthesis, Characterization, and Self-Assembly, First Edition. 

Edited by Nikos Hadjichristidis, Akira Hirao, Yasuyuki Tezuka and Filip Du Prez. 

These complex reaction sequences are avoided in the synthesis of hyperbranched polymers, the second family of dendritic polymers. Hyperbranched polymers with a high molecular weight can be obtained in one-pot self-condensation reactions of ABn monomers without protecting groups, with the tradeoff that control over the molecular weight and branching is much more limited. The random nature of the condensation reaction leads to polymers with many structural flaws and a broad MWD 2) in most cases. 

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Scheme 6.1 General scheme for the synthesis of arborescent polymers. (Reprinted from Progress in Polymer Science, 29, S. J. Teertstra and M. Gauthier, Dendrigraft polymers Macromolecular engineering on a mesoscopic scale, 277-327, 2004, with permission from Elsevier.)...

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